Consider I have a few references from white to yellowish, and I look at them in 2 different lights: a cool-coloured light (white/~6500k) and a warm-coloured light (yellow/~3500k). Firstly, intuitively, I thought that I will perceive the whiter ones to be yellower in yellow light, but I don't -- in fact, it's the opposite: I see the yellower ones whiter in yellow light.
What does it mean? Does it mean that the colour constancy mechanisms of humans notices there's a yellow light and tries to adjust the brain such that I perceive yellowish stuff as white? If so, how come the ones that are intrinsically yellowish are still perceived as white? Does the colour constancy mechanism overestimates how much to correct?